1. Field of the Invention
The present general inventive concept relates to an apparatus and method to inspect display panels, and more particularly, to an apparatus and method to inspect display panels to correctly detect a defect of the display panel itself.
2. Description of the Related Art
Generally, a display panel serves as a display unit for visually displaying data and includes a liquid crystal display (LCD) panel, a plasma display panel (PDP), etc.
The LCD panel is a display unit employing electro-optic properties of the liquid crystals having an intermediate characteristic between a liquid and a solid. That is, the LCD panel controls an amount of light generated from a backlight by moving internal liquid crystals and displays a specific pattern on a screen.
Because a desired pattern may be not appropriately generated due to an external substance or an electric defect of the panel itself in a process for manufacturing the LCD panel, various inspection devices are being developed to detect a defect of the LCD panel.
A conventional inspection device for use in the LCD panel includes a typical backlight, a pattern generator for applying a preset pattern to the LCD panel so that an inspection operation can be performed, a camera for picking up the LCD panel to capture an image of the LCD panel, and a microcomputer for controlling an overall operation of the inspection device.
As described above, the conventional inspection device for use in the LCD panel applies a test pattern to the LCD panel to be inspected so that a defect of the LCD panel can be detected, and then turns on the backlight. Then, the camera picks up the LCD panel so that the image of the LCD panel can be captured. When the image of the LCD panel has been captured, the microcomputer analyzes the captured image and determines whether or not the LCD panel is defective. Types of defects detected by the inspection operation for the LCD panel can be a HIGH defect, an OFF defect, etc. A black color must be entirely displayed when a black pattern is applied to the LCD panel, but light may come out of at least one point of the LCD panel. This case is referred to as the HIGH defect. On the other hand, some region of the LCD panel becoming dark without emitting light may be present when a white pattern is applied to the LCD panel. This case is referred to as the OFF defect.
In addition to a defect of the LCD panel itself when the LCD panel is inspected, the LCD panel can be shown as if it is defective due to an external factor. That is, when the backlight is turned on to inspect the LCD panel, a surface scratch, dust, etc., on a protection film attached to protect the LCD panel in the manufacturing process can cause light transmitted from the LCD panel to be dispersed. In this case, the image captured by picking up the LCD panel displays a defect point due to the dust or surface scratch in the same form as a form in which the LCD panel itself is defective.
Because the conventional apparatus and method for inspecting the LCD panel cannot discriminate a defect of the LCD panel itself from a defect due to a surface scratch or dust, there is a problem in that the LCD panel can be erroneously inspected.